President Trump is set Wednesday to take the first steps toward building his “big, beautiful wall” to keep illegal immigrants out – but a more pressing issue may be dealing with the nearly 2 million criminal aliens who’ve already made it inside America’s borders.

At least 925,000 illegal immigrants had been targeted for deportation but remained in the U.S., as of a 2015 estimate from Immigration and Custom Enforcement. A Department of Homeland Security study, however, said that number is more than doubled – to a staggering 1.9 million – when applied to all criminal aliens in the U.S., not just those ticketed to be kicked out. A criminal alien is any noncitizen – in the U.S. legally or illegally – convicted of a crime. But The Center for Immigration Studies’ Jessica Vaughan has said the vast majority of those aliens are indeed illegals.

Trump began his candidacy by promising the mass deportation of illegals; however, as he emerged as the GOP nominee, and then eventually won the presidency, he softened his position to focus on criminal aliens.

Trump’s actions Wednesday will be the first step in that process. Among other orders, Trump is likely to curb funding to so-called sanctuary cities, beef up the number of border patrol agents and stop the controversial catch-and-release practice in which immigration agents release illegals awaiting removal hearings.

“They’ve been allowed to stay here and take advantage of our generous immigration court system,” Vaughan said. “But the result of letting people go instead of keeping them in custody is they disappear into the woodwork and don’t fear any consequences.”

Of the 925,193 illegal immigrants who’ve evaded a scheduled deportation, 179,040 had a criminal conviction – and 172,135 of those remained at large, according to ICE figures.

In 2015 alone, 19,723 criminal illegal immigrants were released back into the U.S. – including 208 convicted of homicides and more than 900 with sex crime convictions, an ICE analysis showed. Those 19,723 illegals combined for a total of 64,197 convictions.

“Judges are ordering people removed, but they are either skipping out on those orders or ICE is being told not to bother pursuing them because they’re being told they should focus only on people who’ve committed very serious crimes,” Vaughan said.

And the numbers are trending upward. From 2012 to 2015, illegal immigrants set for deportation who remained in the U.S. grew by 20 percent.

“[Obama administration policies] contributed to this sense that our government isn’t serious about enforcing immigration laws,” Vaughan said. “And that’s why I think the executive orders coming today from President Trump are going to go a long way toward changing the calculation that illegal immigrants make – that they can just get away with ignoring a removal order.”

“These people didn’t arrive overnight and this problem didn’t happen overnight, so it’s going to take a few years to make a big dent in that number,” Vaughan said. “But today President Trump is getting the immigration enforcement system back on track.”